Solid-oxide fuel cells (SOFC's) generally comprise a solid electrolyte such as yttria-stabilized zirconia (YSZ) with a positive air electrode, such as described in co-pending application Ser. No. 08/408,953 filed Mar. 22, 1995, on one surface of the electrolyte and a negative fuel electrode (anode) such as a cermet of nickel and stabilized zirconia on the other surface of the electrolyte. In the prior art the anodes have been composed of bulk Ni and YSZ (Ni--YSZ). The main reasons for using Ni--YSZ anodes are the reasonable cost of the materials, the stability and excellent catalytic activity of Ni in fuel gas environments, and the fact that a high density of three-phase boundaries are formed in the cermet, increasing electrochemical reaction rates.sup.(1). There are several problems with Ni--YSZ, however, including sintering and segregation of Ni out of the two-phase structure.sup.(2), performance loss in the presence of sulphur contamination.sup.(3), and poor thermal expansion match with YSZ at high Ni contents.sup.(4). Interfacial reaction kinetics are strongly dependent on the microstructures, i.e. the three-phase boundary length, as determined by the method of fabricating the Ni--YSZ and the YSZ.sup.(1,5).
Several groups have recently reported results on SOFC's employing thin (.about.10 .mu.m) Y-stabilized zirconia (YSZ) electrolytes.sup.(6,7). One of the main advantages of these thin-film-electrolyte cells is that the electrolyte ohmic resistance is low enough at 600.degree.-800.degree. C. for efficient SOFC operation. Reducing the cell operating temperature T.sub.c has been widely discussed as a means for easing materials and processing problems associated with interconnection and gas sealing in SOFC stacks.sup.(8). At T.sub.c .apprxeq.600.degree.-800.degree. C., however, thermally-activated electrochemical reaction rates decrease, increasing electrode interfacial resistance r.sub.i and limiting the SOFC power density. While new methods for improving air-electrode performance have recently been developed.sup.(9), very little is known about Ni--YSZ in this T.sub.c range.